Patey, we are very sorry for your loss, we know exactly what you are going through.
We rescued a Cairn Terrier 15 years ago who had been tied to a post in a garden and when she had a litter of puppies the owner put them in a black bag and dumped it in a river. We had this dog for 8 years, it was the first dog we had with a new born baby and our son grew up with her, she then died when our son was 8 and it was devastating, we knew the time was coming so we bought a jack russel puppy, 2 days after the terrier past away the jack russel wasn't eating and she was having panting fits, we rushed her into the vets and whilst waiting in the waiting room she passed away in my arms, this was awful and it made my wife and son ill.
We then immediately went to the local dogs home and they had a litter of puppies which were only weeks old, we let our son decide on which one and he picked the most troublesome!! She tore up carpets and ripped door seals off but we loved her anyway, we have now had her 8 years and she has only calmed down a bit, a few months ago we went to the rehoming centre to give a Xmas donation and they had a westie which had been locked in a box for 2 years and used as a breeding machine, she had never walked or seen daylight, even though we had no plans for a second dog we couldnt leave her in this cage for Xmas so we adopted her and have now had her 7 months, we taught her to walk and to take treats, still working on the sit though, she cant quite keep concentration.
Our son was so devastated when the terrier and jack russel died that he just lay in his room hugging their blankets and the only time that we saw a smile on his face is when we took him to choose a new puppy.
It will get better as time goes on and when you are ready go and have a look in the rehoming centre, there are so many dogs looking for loving owners such as you.